Hybrid optical and radio frequency phased array antennas

Abstract

Methods and systems for communicating messages through free space are provided. In particular, examples or implementations facilitate communication between moving devices separated by free space. In examples or implementations, a radio-frequency (RF) communication link is first established between the devices. When one device intends to transmit data to another device, the one device, using an RF phased array, determines an angle-of-arrival for RF signals received from the other device. The one device then aims a light source according to the determined angle-of-arrival and transmits the data as an optical signal. In some examples or implementations, the other device at least partly receives, using a light detector, the optical signal and determines an alignment offset from the light detector. The other device then communicates the alignment offset to the one device by a further RF signal so that the alignment can be improved.

What is claimed is: 
     
         1 . A method comprising:
 receiving, by a radio frequency (RF) antenna unit of a first electronic device (FED), a RF signal from a second electronic device (SED), the RF signal having associated thereto an angle of arrival (AOA) at the FED;   aiming a light source of the FED towards the SED in accordance with the AOA of the RF signal;   and   transmitting, by the light source, an optical signal towards the SED, the optical signal encoding a data message.   
     
     
         2 . The method of  claim 1  wherein:
 the FED has a control unit; 
 and 
 the method further comprises:
 determining, by the control unit, the AOA. 
 
 
     
     
         3 . The method of  claim 2  wherein:
 the RF antenna unit includes a plurality of antennae arranged as an array of antennae; 
 receiving, by the RF antenna unit of the FED, the RF signal from the SED includes:
 receiving, by each antenna of the array of antennae, the RF signal, the RF signal having a respective phase shift at each antenna; 
 
 and 
 determining, by the control unit, the AOA includes:
 determining, by the control unit, the AOA in accordance with the respective phase shift of each antenna of the array of antennae. 
 
 
     
     
         4 . The method of  claim 2  wherein determining, by the control unit, the AOA includes:
 determining, by the control unit, the AOA in accordance with a multiple signal classification algorithm. 
 
     
     
         5 . The method of  claim 1  further comprising:
 establishing, by the RF antenna unit, a RF link with the SED. 
 
     
     
         6 . The method of  claim 1  wherein transmitting, by the light source, the optical signal towards the receiving electronic device includes:
 sweeping the light source through a sweep pattern oriented in accordance with the AOA of the RF signal. 
 
     
     
         7 . The method of  claim 1  further comprising:
 receiving, by the RF antenna unit, a further RF signal from the SED, the further RF signal defining an alignment offset; 
 re-aiming the light source towards the SED in accordance with the alignment offset; 
 and 
 transmitting, by the light source, a further optical signal towards the SED, the further optical signal encoding the data message. 
 
     
     
         8 . The method of  claim 1  wherein the light source is a free-space laser. 
     
     
         9 . The method of  claim 1  wherein at least one of the SED and the FED is a satellite. 
     
     
         10 . The method of  claim 1  wherein each of the light source and the RF antenna unit are co-located at the FED. 
     
     
         11 . A method comprising:
 receiving, by a light detector of a first electronic device (FED), an optical signal from a second electronic device (SED), the optical signal encoding a data message and having associated thereto a first detected power and an alignment offset;   transmitting, by a radio frequency (RF) antenna unit of the FED, a RF signal towards the SED, the RF signal encoding the alignment offset;   and   receiving, by the light detector, a further optical signal from the SED, the further optical signal encoding the data message and having associated thereto a second detected power being greater than the first detected power.   
     
     
         12 . The method of  claim 11  further comprising:
 establishing, by the RF antenna unit, a RF link with the SED. 
 
     
     
         13 . The method of  claim 11  wherein:
 the light detector includes a main light sensor and one or more auxiliary light sensors each separated from the main light sensor; 
 and 
 receiving, by the light detector, the optical signal from the SED includes:
 receiving, by the main light sensor, a main light sensor portion of the optical signal having a respective optical power; 
 and 
 receiving, by each of the one or more auxiliary light sensors, a respective auxiliary light sensor portion of the optical signal having a respective auxiliary optical power. 
 
 
     
     
         14 . The method of  claim 13  wherein:
 the FED has a control unit; 
 and 
 the method further comprises:
 determining, by the control unit, the alignment offset in accordance with the respective optical power of the main light sensor portion of the optical signal and the respective auxiliary optical power of each auxiliary light sensor portion of the optical signal. 
 
 
     
     
         15 . The method of  claim 13  wherein the main light sensor is located about at a first predetermined vector with respect to the RF antenna unit and each of the one or more auxiliary light sensors is located about at a respective second predetermined vector with respect to the main light sensor. 
     
     
         16 . The method of  claim 11  wherein at least one of the FED and the SED is a satellite. 
     
     
         17 . A system for communicating a data message comprising:
 a first electronic device (FED);
 and 
   a second electronic device (SED) having a light source and a respective radio-frequency (RF) antenna unit, the SED configured to:
 receive, by the respective RF antenna unit, a RF signal from the FED, the RF signal having associated thereto an angle of arrival (AOA) at the SED; 
 aim the light source towards the FED in accordance with the AOA of the RF signal; 
 and 
 transmit, by the light source, an optical signal towards the FED, the optical signal encoding the data message. 
   
     
     
         18 . The system of  claim 17  wherein:
 the FED has a light detector and a respective RF antenna unit; 
 and 
 the FED is configured to:
 receive, by the light detector, the optical signal from the SED, the optical signal having associated thereto an alignment offset; 
 and 
 transmit, by the respective RF antenna unit, a further RF signal towards the SED, the RF signal encoding the alignment offset. 
 
 
     
     
         19 . The system of  claim 18  wherein:
 the SED is further configured to:
 receive, by the respective RF antenna unit, the further RF signal from the FED; 
 re-aim the light source towards the FED in accordance with the alignment offset; 
 and 
 transmit, by the light source, a further optical signal towards the FED, the further optical signal encoding the data message. 
 
 
     
     
         20 . The system of  claim 19  wherein:
 the FED is further configured to:
 receive, by the light detector, the further optical signal from the SED, the further optical signal having associated thereto a respective detected power being greater than the respective detected power of the optical signal.